Formation of a set of fiber optic connections (i.e., one or more fiber optic connections) typically involves mating a female fiber optic connector with a male fiber optic connector. One conventional female fiber optic connector includes a female multi-fiber ferrule which (i) holds a set of polished fiber ends and (ii) defines a pair of alignment holes (i.e., one alignment hole on each side of the set of polished fiber ends). The female connector further includes a rectangular-shaped female housing which (i) rigidly positions the ferrule therein, and (ii) defines a pair of alignment slots (i.e., one alignment slot on each side of the ferrule).
Likewise, one conventional male fiber optic connector includes a multi-fiber ferrule which holds a similar set of polished fiber ends, and a pair of alignment pins which extend from the ferrule (i.e., one alignment pin on each side of the set of polished fiber ends). The male connector further includes a male housing having a rectangular-shaped base portion in which the ferrule resides, and a pair of alignment beams. The alignment beams extend from the base portion in a parallel manner (i.e., one alignment beam on each side of the ferrule).
During connection, the alignment beams of the male fiber optic connector simultaneously engage the alignment slots of the female fiber optic connector thus bringing the ferrules and their polished fiber optic ends together. The alignment pins extending from the ferrule of the male connector then engage with the alignment holes of the ferrule of the female connector to precisely align the sets of fiber ends to form a healthy and robust set of fiber optic connections.
The housings of some fiber optic connectors hold multiple ferrules in a contained but side-by-side manner. One conventional off-the-shelf family of female and male connectors uses housings, which have been tooled to hold three ferrules. That is, the housing of the female connector holds three ferrules, and the housing of the male connector holds three ferrules such that, when the female and male connectors mate, three times the number of fiber optic connections are formed compared to that formed by the mating of a single pair of ferrules. Another conventional off-the-shelf family of female and male connectors uses housings, which have been tooled to hold four ferrules. Such connectors are well suited for high-density applications such as when connecting a fiber optic circuit board to a fiber optic backplane.
There are different conventional approaches to connecting a fiber optic circuit board to a fiber optic backplane using fiber optic connectors. One conventional approach to connecting a fiber optic circuit board to a fiber optic backplane (hereinafter called xe2x80x9cthe rigidly mounted connector approachxe2x80x9d) uses a simple, straightforward design. In particular, the male fiber optic circuit board connector rigidly attaches to the circuit board (e.g., with screws). When the circuit board inserts into a card cage assembly and engages a backplane, the male fiber optic circuit board connector mates with a corresponding female fiber optic circuit board connector mounted to the backplane. The male connector, which is rigidly attached to the circuit board, stays in place relative to the female connector on the backplane due to the maintained positioning of the circuit board relative to the backplane (e.g., using circuit board levers which hold the circuit board within a card cage assembly mounted to the backplane). Simultaneously, the connectors operate in a spring-loaded manner to enable the ferrules of the connectors to properly align regardless of subtle differences in board tolerances.
Another conventional approach to connecting a fiber optic circuit board to a fiber optic backplane (hereinafter called xe2x80x9cthe floating housing approachxe2x80x9d) uses a spring-loaded male fiber optic circuit board connector having a male housing which loosely attaches to the circuit board but which is toleranced to float in the Z-direction (toward or away from the backplane) and is biased by a spring to always apply force against the backplane when the circuit board is in a fully-engaged position within a card cage assembly. Accordingly, if any of the components of the circuit board and/or the backplane are slightly out of tolerance, the ability of the male housing to float in the Z-direction eliminates placement of additional stresses on the circuit board (e.g., stresses on solder joints of simultaneously connected electrical components) which could compromise connectivity and perhaps damage the boards. Some manufacturers have attempted to remove the connector biasing and to provide a relaxed isolated latching using an added floating body.
Unfortunately, there are deficiencies to the above-described conventional approaches to connecting fiber optic circuit boards and backplanes. For example, in the conventional rigidly mounted connector approach, it is difficult to precisely control all aspects of circuit board and backplane alignment such as card cage and board tolerances, component placement, uniformity from system to system, etc. Accordingly, it is common for circuit boards and backplanes which have rigidly mounted components to encounter high stresses and forces while engaging each other. In some situations, the stresses can be so great that bonds of some components (e.g., solder joints of electrical connectors neighboring fiber optic connectors) can fatigue and fracture. Such a situation may surface not as a completely defective circuit board, but as an intermittent failure resulting in costly field service calls, as well as lost goodwill and a lost reputation for quality.
Additionally, in the conventional floating housing approach, the housing of the connector is typically tooled to hold a particular number of ferrules (e.g., three) and is thus limited in flexibility. That is, the housing is suitable for a particular application but is unsuitable for other applications. To accommodate a different application (e.g., applications which require five ferrules), the manufacturer must retool for the different application, which is an expensive endeavor (e.g., the manufacturer must redefine and retest connector housing layouts and thickness due to changes in holding forces caused by changes in spring densities).
In contrast to the above-described conventional approaches, the invention is directed to techniques for connecting elements using an improved latching apparatus. The apparatus employs a control assembly (e.g., a system of control arms) which operates to connect the elements together in a manner that permits substantial connector movement in the Z-direction, as well as enables easy scalability and customization with minimal or no retooling. With substantial Z-directional movement permitted, there is little or no Z-directional board stress passed on from connectors to other locations (e.g., to electrical connectors having fragile solder joints). Furthermore, such easy scalability enables a manufacturer to offer a variety of connector configurations without incurring significant retooling and redesigning costs.
One embodiment of the invention is directed to a latching apparatus having a guide member, a circuit board attachment member that is configured to attach to a circuit board, and a control assembly. The control assembly is configured to (i) retain the circuit board attachment member within a retaining range of the guide member when the guide member is unlocked from a receptacle member, and (ii) un-restrict the circuit board attachment member such that the circuit board attachment member is movable outside of the retaining range of the guide member when the guide member is locked with the receptacle member. When the circuit board attachment member is mounted to a circuit board (e.g., a daughter card) and when the receptacle member is mounted to another circuit board (e.g., a backplane, a motherboard, etc.), there is little or no transmission of stresses due to tolerance buildups along a Z-axis (e.g., a Z-direction of one of the circuit boards and along the guide member) due to ability of the circuit board attachment member to move outside of the retaining range of the guide member when the guide member is locked with the receptacle member.
Another embodiment is directed to a circuit board module which includes (a) a first receptacle for receiving a guide member, the first receptacle being adapted to receive a floatable mounting mechanism for attachment to a first planar device; (b) a second receptacle for supporting a slideable guide member, the receptacle being adapted for a fixed mounting mechanism for attachment to a second planar device; (c) a guide member slideably coupled to and within the second receptacle for attachment to the first receptacle; (d) a first retention mechanism (e.g., an arm member) provided between the second receptacle and the guide member, to engage the guide member with the second receptacle when the guide member is not coupled to the first receptacle; (e) a second retention mechanism (e.g., another arm member) provided between the first receptacle and the guide member, to engage the guide member with the first receptacle while the second receptacle is still coupled to the guide member; (f) a first separation mechanism (e.g., a defined tab) provided between the first receptacle and the guide member to separate the first retention mechanism from the second receptacle when the guide member is retained to the first receptacle by means of the second retention mechanism; and (h) a second separation mechanism provided between the second receptacle and the guide member, to separate the second retention mechanism when the second receptacle has been re-coupled to the guide member and the first receptacle is being decoupled from the guide member.